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Our newest book, published on May 6, 2015 and available at Amazon.com for $19.95.

The focus of this book is the interactions between energy, ecology, and climate change, as well as a few of the responses of humanity to these interactions. It is not a textbook, but a series of chapters discussing subtopics in which the authors were interested and wished to write about. The basic material is cutting-edge science; technical journal articles published within the last year, selected for their relevance and interest. Each author selected eight or so technical papers representing his or her view of the most interesting current research in the field, and wrote summaries of them in a journalistic style that is free of scientific jargon and understandable by lay readers. This is the sort of science writing that you might encounter in the New York Times, but concentrated in a way intended to give as broad an overview of the chapter topics as possible. None of this research will appear in textbooks for a few years, so there are not many ways that readers without access to a university library can get access to this information.

This book is intended be browsed—choose a chapter topic you like and read the individual sections in any order; each is intended to be largely stand-alone. Reading all of them will give you considerable insight into what climate scientists concerned with energy, ecology, and human effects are up to, and the challenges they face in understanding one of the most disruptive—if not very rapid—event in human history; anthropogenic climate change. The Table of Contents follows: Continue reading →

In response to a growing fear surrounding increasing levels of CO2 in the atmosphere and rapidly dwindling supplies of traditional oil as a source of energy, A. Fulke et al. investigated the CO2 sequestration rate (as a source of CO2 mitigation), the biomass creation (as a source of biofuel), and lipid composition of algae used in the wastewater stabilization ponds of industrial wastewater treatment plants. The green algae species of the algae they found naturally occurring in the wastewater stabilization ponds have a lipid structure equivalent to vegetable oil currently used to produce biodiesel. In the two most dominant algal classes Chlorophyceae and Cyanophyceae, they found four distinct species (Scenedesmus dimorphus, Scenedesmus incrassatulus, Chroococcus sp. and Chlorella sp.) currently being globally explored as sources of biodiesel. They isolated and cultured samples of these four species and examined the biomass concentration, lipid content, and CO2 fixation rates, finding that the samples where all four of these species were present (as opposed to each species cultured alone) had a biomass concentration (g L-1) and lipid content (g g-1) nearly twice as high as any alone, and a CO2 fixation rate (g L-1d-1) at least double individual species cultivations. They concluded that industrial wastewater could support a diverse culture of algal species capable of being used as a source of biodiesel. —Allison Kerley

Fulke et al. collected samples of water from ten different locations in the wastewater stabilization pond at a currently active vehicle manufacturing plant in the western Maharashtra region in India. They found 27 species of Chlorophyceae, 16 species of Cyanophycea, 14 species of Bacillariophyceae, 4 species of Euglenophyceae and 4 species of Chrysophyceae in the wastewater, with a Shannon-Wiener Diversity Index range from 2.91 to 3.66. They used the Nile Red staining method to determine the lipid content and to identify the intracellular lipid content (used in the creation of biodiesel). Four of the algae species found (Scenedesmus dimorphus, Scenedesmus incrassatulus, Chroococcus sp. and Chlorella sp). are currently being globally explored as potential sources of biodiesel, so Fulke et al. chose to further investigate the lipid content and biomass creation during stress and no-stress scenarios. They cultivated each of the species individually in the lab over 14 days, each in a culture with abundant nutrients and in a culture with limited nutrients. They found that upon nutrient depletion, the algae produce more lipids which get trapped within the cell. Cells with a higher lipid concentration are more favorable for biodiesel creation.

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Due to government mandates in repsponse to climate change, ethanol production has steeply increased since 2009, and there are now for 79 billion liters of cellulosic biofuels yearly by 2022.Cellulosic crops such as maize, switch grass, and Miscanthus have been determined to be viable biofuel sources. In order to meet the biofuel target in 2022, cellulosic crop cultivation needs to be expanded and intensified. The impact on land and water use needs to be considered as well. Zhuang et al. (2013) present a data-model assimilation analysis assuming that maize, switchgrass, and Miscanthus can be grown on available U.S. croplands.—Christina Whalen

The current production levels of maize are not enough to be simultaneously used as biofuels and as a food source. The cellulosic crops switchgrass and Miscanthus have been identified as viable alternatives to maize in producing second-generation biofuel. This is staged to work especially well in temperate regions because of their higher biomass productivity and available crop-producing land. Other studies have shown that bioenergy crops have higher land and water efficiencies than food crops do, but the increasing demand of land and water to cultivate these crops hasn’t been researched using ecosystem models.The study uses the terrestrial ecosystem model (TEM) to predict the demand of land and water for growing various biofuel crops so that enough ethanol can be produced to hit the 2022 target. The goal of the study is to analyze the demand for resources rather than to analyze the environmental impact of growing biofuel crops.

The TEM ecosystem model uses gross primary production (GPP) as the core algorithm, which describes the rate at which a plant produces usable chemical energy. The Net primary production (NPP) is the difference between GPP and plant respiration. In order to analyze the productivity of feedstocks and biofuels, the researchers estimated the biomass and biofuel production in terms of harvestable biomass (HBIO) and bioethanol yield. Current and future biofuel production was estimated using conversion efficiencies and currently available and potentially advanced technologies.TEM was run several times at each site in order to achieve model equilibrium. Analyses were conducted on biomass and biofuel yield, water balance, and water use efficiency and were estimated based on simulations.

The results of the model demonstrate that in order to produce 79 billion liters of ethanol from maize grain, there would be a need for 190 million tons of conventional grain and 26.5 million hectares of land, which is equivalent to 20% of total US cropland. The water loss of this production would be 92 km3, but if the maize stover were also used, water would be saved. Because switchgrass has lower conversion efficiency, using this crop would result in a higher demand of biomass. More land and water would need to be used to produce the same amount of ethanol than using maize. Alternatively, Miscanthuswould only require half the amount of land and two-thirds the amount of water used for maize grain in order to produce the same amount of ethanol. Furthermore, with the advanced technologies predicted for future years, even less water and land will need to be used in converting biomass to biofuel. The model experiments demonstrate that switching from maize to Miscanthus will save land and water, but that switching from maize to switchgrass will require more land and water.

This study only predicts ethanol production using available croplands, but recent studies have illustrated that marginal lands could also be a source for cultivating cellulosic crops. Experiments have also shown that switchgrass may be more productive on marginal lands than on traditional croplands. The model may produce some bias because it does not consider the effects of fertilization, irrigation, rotation, and tillage. To strengthen the study, analysis of economic viability, food security, nutritional and ethical concerns, and other environmental consequences and benefits need to be conducted.

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Biofuel cells transforming biological fuels such as ethanol or sugar into electricity are safe and ecofriendly source of power. However, biofuel cells are often limited to low voltage and are insufficient to provide necessary power for daily use. Like other traditional electrolyte batteries, stacking up the biofuel cells may boost their single cell voltage to an applicable level. Miyake et al. (2013) performed experiments on multiple ways to improve the voltage of biofuel cells utilizing fructose as the energy source. When stacking cells, each cell has to be isolated with proper wrapping to prevent short-circuits. The authors layered the biofuel cells with enzyme-modified carbon fabric strips and hydrogel sheets to ensure the ion-conduction between the anode and cathode fabric layers; the hydrogel sheet also served as a fuel tank. The modification effectively improved the performance of both bioanodes and biocathodes and maximizes cell power to 0.64 mW at 1.21V.—Chieh-Hsin Chen

To increase the efficiency and the power of biofuel cells, the authors made three modifications to the cells; to prevent short-circuits due to ion-conduction. The first modification was the preparation carbon fabric anodes, where are multi-walled with carbon nanotubes to increase the reaction surface area; they are heated in 400 °C and immersed in multiple solutions such as D-fructose dehydrogenase to increase the efficiencies. The result of this modification is significant: it almost doubles the current density. In the first modification, the authors also found that the performance of cells is significantly affected by buffer concentration; buffer is added to stabilize the local pH level change caused by the oxidation process. With a stabilized pH level, enzymes in the carbon fabrics perform with the highest efficiency with a 0.5M buffer with maximum current produced at 0.6V of 15.8 mA.

The second modification is the gas-diffusion of carbon fabric cathodes. This process followed the process used for Biliruben oxidase (BOD) cathodes. BOD can catalyze the reaction of O2 to H2O without election transfer mediators. The cathode is also treated with heat and multiple solutions including BOD and a surface coat of carbon nanotube solution to make it hydrophobic. To test the effect, the electrode strip was put in an oxygenic pH 5 buffer testing the electric potential versus the current capacity. The performance of a BOD-modified strip reaches to about 1.9 mA cm-2; the additional carbon nanotube coating onto the BOD-modified cathode strip was enhanced to 2.9mA cm-2. The hydrophobic carbon nanotube coating controls the penetration of excess solution into the carbon fabric electrodes allowing the conduction to optimize. The authors also conclude that control of the buffer concentration may optimize the performance with maximum current of 4.6 mA cm-2 at 0V using a .25M buffer solution utilizing an oxygen supply from the ambient air through the carbon fiber.

The third modification is through double-network hydrogel films that contain fructose. This modification is prepared through a three-step process: first, the formation of one layer hydrogel film, then another layer of film, lastly with loading of 500 mM fructose. The hydrogel film is later treated with three stock solutions to secure the fructose solution in the film. Both cathodes and anodes went through the process of lamination with double-network hydrogel sheet; the lamination provides the cells with moisture, fuel sources, and buffering for the reaction. The cells are tested with 0.74V, which is about the electric potential difference between fructose oxidation and oxygen reduction. The performance of the biofuel cell is fairly good; it reached a maximum power density of 0.95 mW cm-2 at 0.36 V. However, the stability of the cell decreases drastically after a few hours due to drying of the hydrogel. More importantly, the authors found that bending the cell sheet into a cylinder effectively increases the performance of the cell. The laminated bent cell produced a maximum power of 0.64 mW at 1.21V, which is sufficient to light an LED unit. With these types of modification, we may expect a more powerful biofuel cell in the future.

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The currently growing concerns around the world about foreign oil dependency and growing climate change, have contributed to an increasing interest in using bio-fuels as an alternative to fossil fuels such as coal, gas, and oil. The study conducted by Graeme I. Pearman (2013) demonstrates that bio-fuels and bio-sequestration can only make a minor contribution to lowering carbon levels and minimizing net emissions of carbon into the atmosphere. This is done through examining available solar radiation and observing how efficient natural and agricultural ecosystems are in converting that energy to usable biomass. The 11 countries compared in the study are Australia, Brazil, China, Japan, Republic of Korea, New Zealand, Papua New Guinea, Singapore, Sweden, United Kingdom, and United States, with a main focus on the researcher’s homeland, Australia. The objective of the study is to answer the following question: from a biophysical perspective, can using bio-fuels or bio-sequestration of carbon significantly contribute to the future of energy and the reduction of greenhouse-gas(GHG) emissions?—Christina Whalen

The first part of the study focuses on comparing annual rates of solar radiation and respective energy consumption for each country. The results group countries into 3 groups. Group 1, Japan, Korea, and Singapore had energy consumption around 1 en dash 10% of incident (surface) radiation. Group 2, China, U.K., and U.S. had energy consumption around 0.1% and Group 3, Australia, Brazil, New Zealand, Papua New Guinea, and Sweden had energy consumption around 0.1 en dash 0.001% of incident radiation. These comparisons demonstrate the limits that deriving energy from the sun has on meeting national expectations for energy consumption. We can consume much more energy than the sun could ever provide us.

Photosynthetic efficiency is another limit to the use of bio-fuels or bio-sequestration. The pigments in the chloroplast are only activated by certain parts of the solar spectrum, leaving much of the solar radiation unutilized. In addition, more than 50% of photosynthetic products (sugars) are lost through photorespiration. The whole process is only 3.3% efficient in C3 plants and 6.7% in C4 plants.

The study then continues to examine the limitations of bio-fuels regarding energy efficiency captured from natural vegetation and from global crops. Net primary production (NPP) is how much carbon (or energy in this case) remains after the photosynthetic organism has used it for growth and other metabolic functions. In natural environments, a large portion of captured solar energy is used within the community and is vital for a functioning and healthy ecosystem. Thus, human use of this energy will no doubt have negative impacts on preexisting ecosystems. Agricultural ecosystems are constructed for the purpose of providing biomass for human consumption. The main difference between the two types of ecosystems is that a cultivated system inputs fossil fuels, which needs to be considered when accounting for the net production of energy. Comparisons within each of the countries were then made between energy captured annually as net primary production and the national solar radiation and energy consumption rates. The comparison demonstrates the inefficiency of the biochemistry involved in photosynthesis and is also influenced by temperature and water availability. The comparisons also conclude that modifying the NPP of the biosphere could be possible when global scale changes occur to temperature, rainfall, and carbon dioxide concentrations.

Photosynthesis can be more efficient in agricultural crops when there is plenty of water and fertilizer and crop management is most favorable during the peak growth rates. In the study, multiple samples were taken from various countries and locations in order to accurately compare the relative efficiencies of different cropping systems. This is called “tradable production” because the net production is calculated after discarding the roots, leaves, and stems of plants. Sugar cane and wheat crops have the potential to contribute significantly the nation’s energy demand, but have some economic and political setbacks that are not discussed in detail in the paper.

Though natural and agricultural biomass have the potential to provide energy for human use and to offset carbon emissions from fossil fuels, this study demonstrates that there are major limiting factors to this solution including the availability of solar radiation and the efficiency of photosynthesis needed to convert the energy into feedstock. Another limitation is how efficiently biomass can be converted into fuels that are appropriate for existing feedstocks, conversion systems, and applications. Solar radiation on land accounts for 1700 times the amount of energy consumed by humans, but the radiation and the energy demands are not evenly distributed geographically, so this process depends on the redistribution of energy. It also depends on how efficiently solar energy can be converted to meet the demands of humans, which is where photosynthesis becomes a limiting factor. In comparison, agricultural crops may be more efficient at converting solar radiation to a more usable form of energy, but the study demonstrates that wheat, rice, and corn crops have low efficiency rates that are similar to those of natural ecosystems. The only crop that shows a decent amount of efficiency is sugar cane.

The analysis conducted in this study is not meant to completely reject the idea of using crops and natural ecosystems as bio-fuel and bio-sequestration of carbon, butis meant to illustrate that this would require a huge amount of increase in land utilization and/or altering existing crops. Investors in these types of activities and governments seeking policy implementation need to be aware of these so-called “attractive” energy efficiency solutions.

The paper summarizes 12 criteria of assessments of issues raised by the possibility of using bio-fuels as a future energy source and for the bio-sequestration of carbon. The first issue that needs to be examined is the potential for agricultural and forestry capacity to deliver to energy demands and emissions reduction. Another one is evaluating the co-benefits or dis-benefits of developing policies about bio-fuels such as soil productivity, job creation, economic opportunities, international balance of trade, security of energy supply and so on. There also has to be enough net energy to cultivate crops for fuels, to produce fertilizer, transform the energy into chemical energy, and for transporting the subsequent fuel.Another issue to keep in mind is the continuously changing climate and its affect on which bio-fuels are appropriate. Other issues include timing, production location, strategic carbon & nitrogen budgeting, human capacity to convert the energy, competing use of land, costs of production, and social and political realities.

The conclusion of the paper does little to provide the answers to the various questions raised throughout the study, but rather implies that “we” have the knowledge to develop a system to produce bio-fuels and bio-sequestration of carbon from agricultural crops and natural ecosystems, but now we need more efficient biomass that will provide us with the tools we need to power that process.

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Technology for production of biofuels has been a popular research area for many biochemists in the past ten years because finding alternatives to the use of fossil fuels can have important effects on the future of human life. Although the technology is not able to produce low cost, efficient biofuels yet, Borak et al. (2013) promote the possibilities and efficiency of biofuel production through crops. Their “PETRO approach” is used to evaluate the new crops, not only on the capture of solar energy but also the capture of carbon in atmosphere. The reverse of the carbon combustion cycle naturally occurs within plants, which use photosynthesis to convert carbon dioxide from the air to usable fuels. The energy source products from various crops are similar, but the efficiency of conversion of sunlight into energy varies. The authors summed up the total loss of energy during each process and organized data on the final energy content for each crop. They showed that using the PETRO approach for evaluating potential crops as biofuels can lead to more detail-based discussion in the scientific community.—Chieh-Hsin Chen

Because of the depletion of fossil fuels and the atmospheric increase of atmospheric carbon dioxide from combusting the fossil fuels, scientists are eager to find alternative fuels. The two main barriers to production of alternative fuels are the costs and shortage of potential stocks; thus the production of liquid fuels from crops has become one of the top environmental goals for future research. On a fundamental level, the concept of biofuel is replacing the process of mining with the process of agriculture; the process shift is significant because biomass has significantly higher carbon oxidation state than fossil fuels. The approach of biofuel essentially reversed the combustion of carbon-based fuels capturing the byproduct CO2 converting and storing as usable energy via carbon fixation utilizing plants and other terrestrial plant matter.

To further enhance the ability of the biofuel production, a detailed evaluation of efficiency of the crops and productivity of conversion of energy will be useful; however a systematic methodology for evaluation is currently lacking in the field. Different research groups studying in different geographical areas use a variety of non-comparative assumptions and approaches to calculation yields. The data consistency became one of the difficulties for further biofuel research. The authors introduced the Plants Engineered To Replace Oil (PETRO) approach that included the input of raw materials (sunlight, carbon dioxide and water), trace process of conversion by plants, and the output of liquid fuels. Photosynthesis reverses the combustion of fuels and stores the carbon energy along with solar energy in the plant; the production of biofuel extracts and concentrates carbon energy from plants, usually as ethanol, converting it into usable fuel.

Although plants have evolved effective photosynthetic pathway to capture light, they are not as efficient as we would like; the result of evolution does not aim for maximizing the benefits of wither for producing food or fuels. That C3 plants only utilize 4.6% of the solar energy and C4 plants utilize 6.0% suggests substantial room for improvement but even with these low capture levels of photons much of the captured energy is subsequently lost.

The authors looked into the difference in loss of carbon energy between C3and C4 plants in four levels: captured, harvested, purified, and processed. C3 plants lose half of their usable carbon energy in photorespiration and more in respiration. C4 plants lose less in respiration, but C4 plants lose more than half seasonally. Overall the final usable carbon energy in C3 plantsis about 0.69% and 3.0% in C4 plants. But there are also some losses of carbon energy in the processing steps.

Although energy loss in the processing steps is small compared to the loss from photorespiration or seasonality, it is the first step that can be improved through conventional engineering. With careful genetic selection and engineering of crops, we will be ale to control the seasonality and other growth process of crops. The authors introduce data that show the differences in final fuel product of four common crops used in biofuels: maize, soybean, sugarcane, and switchgrass. The final energy content of the four different crops is very similar, but they have significant differences in overall fuel yield. Sugarcane contains the most overall fuel yield and soybean the least.

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The need for renewable fuels is increasing as the fossil fuel crisis becomes more severe. Animal fats, an inexpensive source of triglyceride, are a potential cost-effective feedstock for biodiesel production (Kwon et al. 2012). However, animal fats, which contain up to 6 wt% of free fatty acids (FFA’s), must be pre-treated before undergoing conventional catalytic processes (Crabbe et al. 2001; Naik et al. 2008). Without pretreatment steps, impurities in the feedstock will react with the catalysts and limit the biofuel yield by producing soap. Kwon et al. aim to prove that an efficient non-catalytic biodiesel conversion using only charcoal and CO2is possible. They determined the optimal conditions for this conversion, including temperature, pressure, and feeding ratio of raw materials. Previous studies on non-catalytic conversion suggest an optimal temperature of 250°C, a pressure of 10MPa or higher, and a methanol-to-oil molar ratio of 6:1. In the present study, Kwon et al. determined optimal operating conditions for the conversion of animal fats to biodiesel to be at a temperature of 350–500 °C under ambient pressure, and volumetric flow rates of extracted lipid and methanol (MeOH) to be 10 and 3 ml min–1, respectively. —Shelby Long

Kwon et al. analyzed the production process of biodiesel by transforming animal fat into biodiesel using charcoal and CO2. They obtained cooking oil from a local restaurant, beef tallow and lard from the local slaughterhouse, charcoal from the local market, and MgO–CaO/Al2O3 thatwas generated from magnesium slag from a magnesium-smelting factory. They determined the acid value (AV), an indicator of oil quality, with the following equation: AV = A x c x 56.11/m (A = volume of KOH solution use to titrate sample; c = concentrations of KOH solution; m = sample mass). They first examined the non-catalytic biodiesel conversion of used cooking oil to biodiesel using a pressure reactor. For this experiment they used MgO–CaO/Al2O3 as a catalyst. Kwon et al. carried out the experiment at a temperature of 130–250 °C and maintained pressure by filling the reactor with nitrogen (N2) and CO2. To further examine the effect of temperature on the conversion process they replicated the previous experiment but varied the temperature from 250–500 °C. Kwon et al. replicated the same experiment a third time, but added a virgin catalyst, activated Al2O3, in order to examine the catalytic element effect of MgO–CaO on the transesterification reaction. For their main experiment, Kwon et al. tested the conversion of beef tallow and lard into biodiesel using charcoal. They packed charcoal into an airtight reactor and maintained the temperature at 250–500 °C while oil feedstock, MeOH, and CO2 reaction medium were continuously added into the reactor. The mixture was allowed to settle for 2 hours after the reaction before the contents were analyzed.

Kwon et al. achieved an approximately 98% biodiesel conversion rate of used cooking oil after 30 minutes. This high conversion rate suggests that CO2 can enhance transesterification. CO2 is believed to enhance the efficiency of the transesterification process by accelerating bond dissociations, also known as thermal cracking (Kwon et al. 2009). By examining the biodiesel conversion of used cooking oil, Kwon et al. determined that the conversion rate is more responsive to changes in temperature than to pressure. They also found that non-catalytic biodiesel conversion can be completed using porous materials. The pores, such as those in charcoal, act as small reactors, while the high temperature drives the transesterification reaction. One of the main findings Kwon et al. observed was that under atmospheric pressure and a relatively high temperature, the conversion cost can be decreased by almost 70%, compared to standard commercial processes.

The researchers suggest that the mass decay of lard they observed at the comparatively low temperatures of 120–140 °C may be due to low molecular lipids and moisture in the lard. Also, the thermal decomposition of lard was observed to be lower than that of beef tallow, which may be attributed to its lower amount of saturated fat. In addition, they also found that the thermal degradation pattern for animal fats is similar to that of vegetable oil. The biodiesel conversion efficiency of lard and beef tallow was almost identical at 400 °C. There was no evidence of thermal cracking taking place in the experiment.

Kwon et al. achieved a conversion efficiency of beef tallow and lard into biodiesel of 98.5 (+ 0.5) % under ambient pressure and at temperatures higher than 350 °C. They determined these to be the optimal operating conditions. Based on their observations, the researchers assert that the production of biodiesel using charcoal and CO2 has the potential to be a highly cost-effective biofuel conversion process.